Welding machine



June 27, 1939. BEmERMAN 2,163,930

WELDING MACHINE Filed Aug. 6, 1937 5 Sheets-Sheet 1 INVENTOR.

ATTORNEYS.

@Wwam June 27, 1939.

E. s. BEIDERIMAN WELDING MACHINE 5 Sheets-Sheet 2 Filed Aug. 6, .1937

INVENTOR. BY m Iii 16W- 5mm y ATTORNEYS.

June 27, 1939. B'E ERMAN 2,163,930

I WELDING MACHINE Filed Aug. 6, 1937 I 5 Sheets-Sheet 3 Cg JVIENTOR.

ATTORNEYS.

e 1939- E. G. BEIDERMAN 7 2,163,930

WELDING MACHINE Filed Aug. 6, 1957 s Sheets-Sheet 4 ATTORNEYS June 27, 1939. BEHDERMAN 2,163,930

WELDING MACHINE Filed Aug. 6, 1937 5 Sheets-Sheet 5 ATTORNEYS Patented June27, 1939 PATENT OFFICE WELDING MACHINE Edward G. Beiderman, Detroit, Mich., assignor to General Motors'corporation, Detroit, Mich, a corporation of Delaware Application August 6, 1937, Serial No. 157,769

8Claims.

This invention relates to a welding machine and more particularly to a combined welder and work conveyor which operates automatically.

It is the object of this invention to produce a 5 welding machine which is more efllcient and economical in operation and welds better than those machines heretofore used.

In the drawings:

Fig. 1 is a plan view showing the combined 10 welder and work conveyor.

Fig. 2 is avertical section through the work conveying apparatus showing the welding machine in elevation.

Fig. 3 is a detail vertical sectional view showl5 ing a modified butfprei'erred form of the device for holding the work in position upon the jig during the welding operation.

Fig. 4 is a side elevation partly in section showing the welding machine and parts of the con veyor adjacent thereto.

Fig. 5 is a fragmentary side elevation or the welding head and jig.

Figs. 6, 7, 8, 9, .10 and 11 are details showing the operation of the welding head and the con- 25 trols therefor.

Fig. 12' is an enlarged detail showing the several positions of the upper welding electrode during the welding operation. P

This invention relates particularly to a repeat spot welding machine wherein the work to be welded is loaded on a conveyor at a loading station, the conveyor then carries the work to the welding machine where it is welded, and then the conveyor carries the work on to the unloading 35 station. Any suitable and well-known conveyor may be used for carrying the work through the above-mentioned course of travel.

By way or description rather than of limitation, there is shown a conveyor comprising a trackway in the form of a pair of flat tracks I and 2 which are positioned side by side having their adjacent ,edges spaced to form the slot 3. The tracks I and 2 are endless and as herein shown extend about an elliptical course. The 45 tracks are supported by a frame generally designated I. A traveling conveyor chain [is supported beneath the tracks I and 2 and driven by any suitable driving mechanism such as the Reeves drive. generally designated 6, havinga 50 driving gear I which meshes with the conveyor chain 5. A plurality oi jigs, generally designated 8, are slidably mounted upon the tracks I and 2. Each jig is connected at longitudinally spaced points to the conveyor chain 5 by the pins 8. 55 Thus, the conveyor chain drives'the jigs 8 along the tracks I and 2 about an elliptical course. Each jig comprises a copper bar l2 which is fixed intermediate a pair of angle iron plates l and II which slide along the tracks I and 2. The copper bar l2 serves as the lower electrode dur- 6 ing the welding operation.

' The'work to be welded in this particular form of the machine comprises a pair of metal plates l3 and I having flanges l and I6 respectively. The plates l3 and H are arranged to be mounted over the electrode l2 and clamped or otherwise secured to the jig with their flanges l5 and I6 pverlapping as shown in Fig. 2. A pair of opposed rollers I! and I8 are mounted upon opposed obliqueplungers l9 and 20 which are urged towards each other and against the work by the springs 2| and 22. During the welding operation the rollers H and I8 press the plates l3- and I4 tightly against the electrode l2.

.Ihis invention contemplates a repeat welder which will spot weld the work at spaced points while the work is moving through the welder. The work preparatory to the flow of current therethrough from one electrode to the other should first be tightly pressed together, and this pressure should continue during the flow of cur rent through the electrodes and work to heat the workto welding temperatures and should continue for a suitable time after the current is. shut ofi to finish the welding operation.

It is the object of this invention to efiect the weld more-accurately and moreeificiently than heretofore known in the art. To eiiect the weld-. ing operation it is proposed to use an upper electrade which engages the work and presses it against the -lower electrode. The upper electrode holder and tip are arranged to travel with the work throughout the period that the electrode is .in contact with the same. To this end it is pro posed to use an, upper electrode holder 25 having an electrode tip 26. The upper electrode holder 25 takes the form of a plunger which is mounted for rectiiinearly reciprocating motion in the cylinder ii. ihe cylinder 21 is pivotally mounted at its upper end 28 on the pin 29 which is carried by the fixed bracket 30. The pin 29 extends across the line of travel of the work and thus permits the cylinder, electrode holder 25 and tip 26 to swing forwardly in the direction of travel of the work and rearwardly in the reverse direction. 5 The cylinder 21 is swung reversely of the direction of travel of the work by the compression spring 3| which is mounted over a rod 32 which is pivotally connected as at 33 to the cylinder 21 at one end and has a sliding swivelling connection with the bracket 30 as at 34. During the weldingoperation and while the electrode tip 25,

' holder 25, and cylinder 21 are traveling with the work, the rod 32 slides longitudinally through the swivel connection 34 compressing the spring- 3|. After the electrode tip 26 is retracted from the work the spring 3| returns the cylinder, holder and tip to original or starting position, shown'in' Fig. 6. The return stroke of these members is stopped by the nut 19 screwed on the threaded end of the rod 32. The length of the .return stroke can be varied by screwing or ad- 6 electrodes weld the work (this plane, as herein shown, happens to be a vertical plane and is perpendicular to the horizontal flanges I5 and I6) and reversely thereof and so that it can reciprocate toward and away from the work in this same plane.

Any suitable means can be used for reciprorcating the upper electrode 25 and controlling the flow of current from one electrode to the other and through the work. The reciprocation of the reciprocating electrode 25 and the flow of current through the work from one electrode to the other must be timed or synchronized. However, by piv- January 13, 1936, or one similar thereto, such,

as shown in'the application of John Abplanalp, Serial No. 65,332, flied February 24, 1936, wherein an automatic air. operated valve is combined with other mechanism for automatically and pneumatically bringing the electrodes together, automatically switching on the current and properly timing the same, and automatically withdrawing the electrodes and then repeating this cycle of operation. Such an automatic air operated valve is controlled by the bell crank valve lever 35 which is pivotally supported on the frame of the machine and. which is' actuated by cams 36 and 37 positioned at the front and rear .ends respectively of each jig 8. The secondary or welding circuit is completed from the transformer 38 through the conductor bar 39 to the flexible laminated spring the plunger 46 which is reciprocably mounted in the air cylinder 41 which is connected to a source of compressed air or other fluid 'by the line 48. The valve which controls the admission of fluid under pressure into the cylinder 41 is controlled by the bell crank 49 pivotally supported on the frame of the welding machine. This bell crank 49 is also operated by the cams 36 and 31 carried by each of the jigs 8.

The operation of the device .will now be described. The jigs 8 are moved continuously along the tracks I and 2 in an elliptical course by the conveyor chain 5 and drive 6. The portion of the trackway I and 2 at and for a short distance to the left and right (Fig. 1) of the welder electrodes is preferably straight so that the work I3 and I4 travels in a rectilinear path .through the welder. The straightaway portion of the slot 3 extends roughly from point 14 to point 15. It will be noted that the metal plates-l3 and I4 curve inwardly at their outer ends as at I I. -Since the welding tip 26 travels fore and aft in a sub-. stantially rectilinear path, the jig l2 and the work must be shifted so that the electrode tip 26 can negotiate the curves H while traveling rectilinearly.- To this end the trackways I and 2, and particularly the guiding groove 3, is curved along two short portions of its length as at I2 just to the left of the straightaway portion 14, 15 and as at 13 just to the right of this straightaway portion. The curved portions I2 and 13 of the groove 3 correspond to the curvature of the end portions H of the work. These curved portions ll-and l3 cooperate with the pins 9 to shift the jig as the work enters and leaves the electrodes so that the curved ends H of the work and jig will travel rectilinearly during each welding operation while the work is clamped between the electrodes. When the forward end of the jig reaches the electrode, the forward'pin 9 enters the straightaway portion I4, 15 and the rear pin 9 is in the curved portion 12 of the slot 3. As the jig travels the rear pin 9 cooperates with the groove 3 to continuously straighten out the jig as it travels by the electrode 26. As the rear end of the jig reaches the upper electrode 26, the rear pin 9 is in the straightaway portion of the slot 3 and the front pin 9 enters the curved portion 13 of the slot 3. Thus, the forward pin 9 now cooperates with the curved portion '13 of the slot to swivel the jig about rear pin 9 and straighten the jig out as the curved rear end of the work travels by the upper electrode, that is, the pins 9 cooperate with the slot 13 to shift the jig and work so that the area of the work clamped between the electrodes travels approximately in a straightline while clamped between the electrodes. The lower electrode l2 moves in a rectilinear path across the direction of reciprocation of the upper electrode 25 and does not move either upwardly or down-. I

wardly. The work l3 and is loaded on theji'g at any point prior to reaching thewelder.

'As shown in Fig. 6 the loaded jig 9, traveling in the direction of thearrow, is about to pass under the upper electrode .25. At this time both bell crank levers 35 and 49 are in the position shown in the full lines. As soon as the cam 35, swings bell crank lever 49 to the dotted line position, Fig. 6, fluid under pressure is admitted into the cylinder 41 and the spool 44 is-forced downwardly to the dotted line position, Fig. 6, to the full line position, Fig. 3, thus pressing the flanges l 5 and I6 together and tightly down upon the upper face 59 of the lower electrode l2. As the jig 8 travels further in the direction of the arrow, Fig. 6, the. cam36 next swings the bell crank lever 35- counter-clockwise to the position i shown in Fig. 7.

above mentioned Beiderman and Abplanalp ap 75 plications, causing the properly timed reciprocation of the upper electrode 25 and flow of current from one electrode to the other through the work. As soon as the lever 35, which controls the automatic air valve, is swung to the position shown in Fig. '7, the upper electrode is,projected downwardly by the admission of fluid under pressure into the cylinder 21 and the electrode tip 26 engages the work to the left of vertical or center line position as shown in Fig. 12.

The position of the electrode 26 as it engages the work is shown by the line A. As soon as the electrode 25 engages the work l5 it immediately travels in the direction of the arrow with 'the work thereby causing the electrode 25 and cylinder 26 to swing counter-clockwise about the pin 29. Before reaching the center line position,

preferably when the electrode 25, 26 reaches theposition indicated by line B, the welding circuit is closed and current flows from the electrode'2'6 through the work to the lower electrode l2. The current continues to flow until the electrode 25, 26 swings past center to the position indicated by the line C. At this time the current is automatically turned off, that is, the welding circuit broken by any suitable means, preferably such as described in the above-mentioned applications. However, the fluid pressure inthe cylinder 21 is maintained thus holding the electrode 26 in contact under pressure with the work l3, l4 until it reaches a point D whereupon the fluid pressure is released from the cylinder 21 and the electrode-26 retracted from the work l5, I6. As soon as the electrode 26 is disengaged from the work l5, 16, the compression spring 3| expands and immediately swings the cylinder 21 and electrode 25 to the left, as viewed in Fig. 12, back to the starting position, shown in Fig. 6. The fiuid pressure in the air cylinder 21, that is, the pressure that the electrode 26 exerts against the work 15 is substantially constant from the position A through the center line position and to the point indicated by line D whereupon it is retracted from the work. This welding cycle is repeated and the plates I3 and I4 spot welded throughout the length of flanges I 5 and I6 and approximately along the longitudinal center line of these flanges.

This cycle of welding operation, to wit: the projection of the electrode 26 into engagement with the work, the travel of the electrode 26 with the work, and the swinging of the same in the cylinder 21 about the pivot 29, the fiow of the welding current through the electrodes and the work, and finally the retraction of the electrode from the work is repeated by the mechanism described in the above-mentioned copending application, and this cycle is continued until the cam 31, as the work travels in the direction of the arrow, Fig. 11, swings the lever' 35 from the full line position to the dotted line position whereupon the electrode 26 is retracted, the

electrode 26 and cylinder 21 swung to the left or starting position by spring 3|, and the switch of the primary welding circuit turned to of! position. Before the cam 31 reaches the bell crank 35 it first swings the bell crank 49 from the position shown in Fig. 10 to that shown in Fig. 11, thus exhausting the fiuid'under pressure from the cylinder 41 which causes the spool 44 to be lifted from the work. v

It will be noted that during the engagement of the upper electrode 26 with the work,, the

electrode not only swings about the pivot 29 but that it travels rectilinearly inwardly of the cylinder 21 until it reaches center line position whereupon it again travels outwardly of the cylinder 21 until it reaches the position indicated by the line D. Y

It will be noted that the electrode tip 26, due to the fact that it is mechanically rather than manually supported, has a rolling contact with the work, and the same points on the surface'of the electrode tip 26 engage the work during each welding cycle. This causes the lower ends of the electrode tips 26 to mushroom or wear along an approximately cylindrical surface. This not only at all times insures a point contact between the electrode contact and the tip which concentrates the welding heat but also in actual operation has given the electrode tips an appreciably greater life.

I claim:

1. In an electrical welding apparatus the combination comprising a support and an electrode swingably and reciprocably mounted on said support .for engaging one side of the material to be'welded, said electrode being swingable in the direction of travel of said work and reversely thereof and reciprocable toward and away from one side of the material transversely of the direction of travel of the said material, a second electrode opposed to said first electrode for engaging the opposite side of said material and cooperating with said first electrode to clamp the material during the welding operation, mechanism for feeding the material'to be welded unidirectionally, and means for reciprocating said first electrode, said means during each cycle or operation of the apparatus projecting said first electrode into engagement with said material to be welded whereby said material is clamped between the said electrodes for welding and serves as the sole means for advancing the swinging electrode with said material whereupon said means retracts the first electrode from the said material, and means for swinging the said electrode reversely of the direction of travel of said material after welding to its initial position.

2. In an electrical welding apparatus the combination comprising a support and an electrode swingably and reciprocably mounted on said support for engaging one side of the material to be welded, said electrode being swingable in the direction of travel of said work and reversely thereof and reciprocable toward and away from one side of the material transversely of the direction of travel of the said material, a second electrode opposed to said first electrode for engaging the opposite side of said material andv cooperating with said first electrode to clamp the material during the welding operation, mechanism for continuously feeding the material to be welded unidirectionally, and means'for reciprocating said first electrode, said means during each cycle of operation of the apparatus moving said first electrode into engagement with said material to be welded whereby said material isclamped between the said electrodes for welding and serves as the sole means for advancing the swinging electrode with said material whereupon said means retracts of the direction of travel of said material after welding to its initial position.

3. In an electrical welding machine for welding advancing work, opposed electrodes for clamping the work on opposite sides and advancing with the work, a support for one electrode pivoted to swing forwardly in the direction the work advances and reversely thereof, and aholder for said same electrode mounted on said pivoted support for reciprocation toward and away from said work and other electrode whereby said reciprocating electrode can be projected against said work to clamp the work against said other electrode, the said reciprocable electrode as thus engaged with the work being advanced solely by and with said work to swing the support and holder about said pivot until said electrode is retracted to release said work.

4. In an electrical welding machine for welding advancing work, opposed electrodes for clamping the work on opposite sides and advancing with the work, a support for one electrode pivoted to swing forwardly in the direction the work advances and reversely thereof, and a holder for said same electrode mounted on said pivoted support for rectilinear reciprocation toward and away from said work and other electrode whereby said reciprocating electrode can be'projected against said work to clamp the work against said other electrode, the said reciprocable electrode as thus engaged with the work being advanced solely. by and with said work to swing the support and holder about said pivot until said electrode is retracted to release said work, and means operable after the electrode is retracted from the work to swing the support and electrode holder about said pivot reversely of the direction of travel of said advancing work.

5. In an electrical welding machine for spot welding advancing work, opposed electrodes for clamping the work .on opposite sides and advancing with the work, one of said electrodes bein arranged to travel rectilinearly and support the work in a single plane during the welding opera-.

tion, a support for the other electrode pivoted to swing forwardly in the direction the work advances and reversely thereof, and a. holder for said other electrode slidably mounted on the said pivoted support for reciprocation toward and away from said work and first mentioned electrode whereby said reciprocating electrode can be projected against said work to clamp the work against said first mentioned electrode, the said reciprocable electrode as thus engaged with the -,work being advanced solely by and with said work during welding to swing said support and holder about said pivot until said reciprocating electrode is retracted to release said work and whereby the portions of said electrodes in contact with the work travel in parallel planes spaced a distance equal to the thickness of the work. Y

6. In an electrical welding machine for welding work which advances relative to the weldin machine during welding, a frame for said machine, opposed electrodes for clamping the work on opposite sides, the first of said electrodes serving as a support for the work, a support for the second of said electrodes pivoted on the said frame to swing forwardly in the direction of relative movement between the work and the frame during welding and reversely-thereof, a holder for the said second electrode mounted on said pivoted support for reciprocation toward and away from said work and first electrode whereby the said reciprocating electrode can be projected against the work to clamp the work against said first electrode and remain in contact with the work during said relative movement between the work and the welder frame whereby the frame and work during their relative movement serve as the sole means for swinging the support and holder about the said pivot until the said electrode is retracted to release said work.

7. In an electric welding machine for making a line of spot welds, a combination of means for supporting and moving work having a planular surface and including one electrode and a companion electrode continuously reciprocating at substantially right angles to the work, said electrode adapted tomomentarily engage and grip the planular work and pass a shot of electric energy through the work while traveling along therewith, the reciprocation of the electrode serving to separate the electrode from' the work and means for returning the electrode to its initial position from which it repeats its said operation, whereby aline of spot welds is afforded whose spacing is dependent upon the speed of travel of the work and the rate of reciprocation of the electrode.

8. In an electric welding machine for making a line of spot welds, means for supporting, and moving the work including one electrode which travels continuously in one direction and a companion electrode which is continuously reciprocating while in operation, said companion electrode adapted to momentarily engage and grip the work and travel along with the work and the electrode and then, upon the reverse movement of the electrode, release the work, means for automatically returning the electrode to its initial position before the electrode again moves into contact with the work in its repeat operation, whereby a line of spot welds is afforded whose spacing is dependent upon the speed of travel of the work and the rate of reciprocation of the electrode.

EDWARD G. BEIDERMAN. 

